On the Noise Path Determination With the Noise Source Modulation Technique

The fundamental properties and key parameters of the noise source modulation technique (NSMT) to determine the electromagnetic noise path are discussed. The basic idea behind the NSMT is to apply a known time variation (modulation) to one of the possible noise paths and to observe its effect at the noise victim location. Different modulations can be applied to different noise paths simultaneously. Based on the type and amount of noise modulation at the victim location, the noise path can be determined. An experiment in ideal conditions has been conducted where two cables carry the same amount of common mode current but only one is the main noise path to the victim. By comparing the path index with the measured insertion loss between cables and receiving antennas, the correctness of the NSMT to determine the noise path is confirmed.